Backscatter stray light detection apparatus and method

Abstract

The application relates to the field of optical measurement, and discloses a backscattering stray light detection device and method, wherein the light beam emitted by a light source module is processed by a light beam processing module, and a light splitting panel divides the light beam into a transmission light beam and a reflection light beam. The transmission light beam enters a unit to be measured to generate backscattering stray light, and the reflection light beam is absorbed by a light absorption module to prevent the reflection light beam from interfering with the measurement result. In addition, a light beam collecting module collects the backscattering stray light returned from the unit to be measured, and the backscattering stray light is detected by a detector module. The design not only reduces the influence of external stray light, but also improves the sensitivity and accuracy of detection through the synergistic effect of the light absorption module and the light beam collecting module, and can improve the detection level to 10 ‑10 W orders of magnitude, providing more accurate data for gravitational wave measurement, and improving the accuracy and reliability of gravitational wave detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical measurement, and more particularly, to a backscattering stray light detection device and method. BACKGROUND

[0002] Gravitational wave detection is one of the frontiers of contemporary physics research, and the inter-satellite laser interferometry technique is the key to achieving high-precision gravitational wave detection. In this technique, the telescope is one of the core payloads and is crucial to improving the efficiency of the light beam transmission between the satellites. In order to detect gravitational wave signals in the frequency band of 0.1 mHz to 1 Hz, based on an inter-satellite laser interferometry arm length of about 170,000 kilometers, the inter-satellite displacement measurement accuracy needs to be improved to the order of picometer per square root of hertz (pm / Hz 1 / 2 ) level. Such extremely high accuracy requirements pose great challenges to the design and manufacture of the telescope, especially in terms of stray light control.

[0003] Currently, the inter-satellite laser interferometry system generally adopts a laser transceiver multiplexing design. Under this design, when the 4-watt transmitted laser reaches the remote satellite, the received power is only on the order of 10 nanowatts. Under such weak signal conditions, the backscattering of the receiving end telescope can have a significant impact on the final beat frequency signal. In order to ensure measurement accuracy, the stray light (mainly backscattering) of the entire system needs to be controlled below 10 -10 watts. However, the traditional testing method cannot effectively eliminate the influence of external stray light on detection, resulting in aliasing between external stray light and backscattering light, which seriously affects the accuracy of stray light measurement. This problem restricts the further improvement of the performance of the telescope and limits the application potential of the inter-satellite laser interferometry system in gravitational wave detection. SUMMARY

[0004] To reduce the influence of external stray light in backscattering measurement and improve the accuracy of gravitational wave measurement, the present application proposes the following technical solutions:

[0005] In a first aspect, the present application proposes a backscattering stray light detection device, comprising:

[0006] A light source module for emitting a light beam.

[0007] A light beam processing module for performing shaping, collimation and / or expansion processing on the light beam emitted by the light source module.

[0008] A light splitting panel for splitting the light beam processed by the light beam processing module into a transmitted light beam and a reflected light beam.

[0009] A unit to be measured arranged on the transmitted light path of the light splitting panel for receiving the transmitted light beam and generating backscattering stray light.

[0010] A light absorption module is arranged on the reflected light path of the light splitting plate and used for absorbing the reflected light beam.

[0011] A light beam collection module is arranged between the light splitting plate and the detector module and used for collecting the backscattered stray light returned from the unit under test and reflected by the light splitting plate.

[0012] A detector module is connected with the light beam collection module and used for receiving and detecting the backscattered stray light collected by the light beam collection module.

[0013] As a preferred technical solution, the reflected light path between the light splitting plate and the unit under test and the reflected light path between the light splitting plate and the light beam collection module are communicated through a continuous light shield.

[0014] As a preferred technical solution, the light splitting plate is a circular plate with a diameter of 25 mm and a thickness of 10.06 mm.

[0015] As a preferred technical solution, the light splitting plate comprises an incident surface and an exit surface.

[0016] The incident surface of the light splitting plate is coated with an anti-reflection film, and the exit surface is coated with a semi-transmissive and semi-reflective film.

[0017] The light splitting plate is arranged obliquely so that the light beam is incident on the light beam incident surface at an angle of 50°.

[0018] As a preferred technical solution, the incident surface and the exit surface of the light splitting plate are both provided with a light transmission aperture.

[0019] The light splitting plate is coated with a black coating in the area other than the light transmission aperture.

[0020] As a preferred technical solution, the light absorption module comprises a light trap, and the residual reflectivity of the light trap is less than 10 -6 The following.

[0021] As a preferred technical solution, the light beam collection module comprises a lens and a diaphragm.

[0022] The lens is installed on the reflected light path of the light splitting plate, and the focal point thereof is located on the detector surface of the detector module.

[0023] The diaphragm is arranged on the light path between the lens and the detector module and used for eliminating other stray light propagating along the light path.

[0024] As a preferred technical solution, the detector module comprises a phototube and an amplifier.

[0025] The phototube is used for converting the received light signal into an electric signal.

[0026] An amplifier amplifies the electrical signal output by the photocell.

[0027] As a preferred technical solution, the light beam emitted by the light source module is a 1064nm laser.

[0028] In a second aspect, the present application further provides a backscattered stray light detection method, which is applied to the backscattered stray light detection device according to any one of the first aspect, and comprises:

[0029] The light source module emits a light beam.

[0030] The light beam emitted by the light source module is shaped, collimated and / or expanded by the light beam processing module.

[0031] The light beam processed by the light beam processing module is divided into a transmitted light beam and a reflected light beam by the light splitting plate.

[0032] The unit to be measured is arranged on the transmitted light path of the light splitting plate, receives the transmitted light beam and generates backscattered stray light.

[0033] The light absorption module is arranged on the reflected light path of the light splitting plate to absorb the reflected light beam.

[0034] The light beam collection module is arranged between the light splitting plate and the detector module to collect the backscattered stray light returned from the unit to be measured and reflected by the light splitting plate.

[0035] The detector module connected to the light beam collection module receives and detects the backscattered stray light collected by the light beam collection module.

[0036] The present application has at least the following beneficial effects:

[0037] The light beam emitted by the light source module is shaped, collimated and / or expanded by the light beam processing module to form a light beam suitable for subsequent measurement. Then, the light splitting plate divides the processed light beam into a transmitted light beam and a reflected light beam. The transmitted light beam enters the unit to be measured to generate backscattered stray light, while the reflected light beam is absorbed by the light absorption module to prevent it from interfering with the measurement results. In addition, the light beam collection module collects the backscattered stray light returned from the unit to be measured and detects it through the detector module. This design not only reduces the influence of external stray light, but also improves the sensitivity and accuracy of detection through the synergistic effect of the light absorption module and the light beam collection module, which can improve the detection level to 10 -10 W order of magnitude, providing more accurate data for gravitational wave measurement and improving the accuracy and reliability of gravitational wave detection. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1Structure diagram of the backscattered stray light detection device provided in Embodiment 1.

[0039] Figure 2 Structure diagram of the backscattered stray light detection device provided in Embodiment 2.

[0040] Figure 3 Structure diagram of the light splitting plate provided in Embodiment 2.

[0041] Figure 4 Flow diagram of the backscattered stray light detection method provided in Embodiment 3.

[0042] Among them, the light source module-1, the light beam processing module-2, the light splitting plate-3, the unit to be measured-4, the light absorption module-5, the light beam collecting module-6, the detector module-7, and the light shield-8. DETAILED DESCRIPTION

[0043] The preferred technical solutions are described below with reference to the accompanying drawings and preferred technical solutions, and other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure in the specification. The present application can also be implemented or applied by means of other different specific embodiments, and each detail in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be understood that the preferred technical solutions are only for illustration of the present application, and are not intended to limit the protection scope of the present application.

[0044] It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present application in a schematic manner, and only the components related to the present application are shown in the diagrams, not the number, shape and size of the components when actually implemented. The actual implementation of each component may be a random change in type, number and proportion, and the component layout pattern may also be more complex.

[0045] In the following description, a large number of details are discussed to provide a more thorough explanation of the embodiments of the present application, however, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details, and in other embodiments, the known structures and devices are shown in the form of block diagrams rather than in the form of details, to avoid making the embodiments of the present application difficult to understand.

[0046] Embodiment 1

[0047] This embodiment proposes a backscattered stray light detection device, as shown in Figure 1 Figure 1 ​The structure diagram of the backscattered stray light detection device provided in the embodiment is shown in the figure. The device comprises a light source module 1, a light beam processing module 2, a light splitting plate 3, a unit to be measured 4, a light absorption module 5, a light beam collecting module 6 and a detector module 7.

[0048] In the implementation process, all components of the backscattered stray light detection device except the unit to be measured 4 are placed in a black box, and the inner wall is painted black. The light source module 1 emits a light beam, which then enters the light beam processing module 2. In this module, the light beam is processed by shaping, collimating and / or expanding to achieve the required characteristics. The processed light beam reaches the light splitting plate 3, which splits it into two paths: one transmits the light beam into the unit to be measured 4, and the other reflects the light beam into the light absorption module 5 to be absorbed. The unit to be measured 4 receives the transmitted light beam and generates backscattered stray light, which returns from the unit to be measured 4, is reflected by the light splitting plate 3, and is collected by the light beam collecting module 6 arranged between the light splitting plate 3 and the detector module 7. The light beam collecting module 6 transmits the collected backscattered stray light to the detector module 7. The detector module 7 receives and detects the backscattered stray light signal from the light beam collecting module 6 and obtains relevant performance index data. During the entire process, each module needs to work precisely to ensure that the detection device can work normally and obtain reliable measurement results.

[0049] It can be understood that the backscattered stray light detection device proposed in the embodiment processes the light beam emitted by the light source module 1 by shaping, collimating and / or expanding in the light beam processing module 2 to form a light beam with characteristics suitable for subsequent measurement. Then, the light splitting plate 3 splits the processed light beam into a transmitted light beam and a reflected light beam. The transmitted light beam enters the unit to be measured 4 to generate backscattered stray light, while the reflected light beam is absorbed by the light absorption module 5 to prevent it from interfering with the measurement results. In addition, the light beam collecting module 6 collects the backscattered stray light returning from the unit to be measured 4 and detects it through the detector module 7. This design not only reduces the influence of external stray light, but also improves the sensitivity and accuracy of detection through the synergistic action of the light absorption module 5 and the light beam collecting module 6, which can improve the detection level to 10 -10 W order of magnitude, providing more accurate data for gravitational wave measurement and improving the accuracy and reliability of gravitational wave detection.

[0050] Embodiment 2

[0051] This embodiment improves the backscattered stray light detection device proposed in Embodiment 1. As shown in the figure, Figure 2 Figure 2 The structure diagram of the backscattered stray light detection device provided in the embodiment is shown in the figure

[0052] ​In this embodiment, the reflected light path between the light splitting plate 3 and the unit to be measured 4, and the reflected light path between the light splitting plate 3 and the light beam collection module 6 are connected through a light shielding cover 8. The inner diameter of the light shielding cover 8 is the same as the diameter of the light beam inside, and the inner wall is coated with a black coating.

[0053] It can be understood that the light shielding cover 8 can effectively block the stray light on the light splitting plate 3 and the light beam collection module 6, and avoid the stray light entering the detector module 7, thereby improving the signal-to-noise ratio of the detection system. The black coating can absorb the stray light, further reducing the interference of the detector module 7.

[0054] In this embodiment, the light beam emitted by the light source module 1 is a 1064nm laser beam.

[0055] In this embodiment, as shown in Figure 3 The light splitting plate 3 is a circular plate with a diameter of 25mm and a thickness of 10.06mm. The light splitting plate 3 includes an incident surface and an exit surface. The incident surface of the light splitting plate 3 is coated with an anti-reflection film, and the exit surface is coated with a semi-transparent and semi-reflective film. The light splitting plate 3 is inclinedly arranged so that the light beam is incident on the light beam incident surface at an angle of 50°. The incident surface and the exit surface of the light splitting plate 3 are both provided with a light transmission aperture, which is an elliptical aperture with a major axis of 7.78mm and a minor axis of 5mm. The light splitting plate 3 is coated with a black coating in the area other than the light transmission aperture.

[0056] It can be understood that selecting a light splitting plate 3 with appropriate size can meet the requirements of light path design and device integration, and ensure that the light splitting plate 3 will not be deformed or damaged when subjected to the light beam, thereby ensuring the stability and reliability of the detection system. The anti-reflection film can improve the transmittance of the incident light beam, and the semi-transparent and semi-reflective film can separate the transmitted light beam and the reflected light beam, and ensure that the intensity of the reflected light beam is moderate. The inclined arrangement of the light splitting plate 3 can avoid direct reflection into the detector, further improving the signal-to-noise ratio of the detection system. The light transmission aperture can ensure the smooth entry and exit of the light beam into the light splitting plate 3, and the black coating can absorb the stray light on the surface of the plate, thereby avoiding the stray light entering the detector module 7 and improving the detection sensitivity.

[0057] In this embodiment, the light absorption module 5 includes a light trap, and the residual reflectivity of the light trap is less than 10 -6 The following.

[0058] It can be understood that the light trap can effectively absorb the reflected light beam, ensure that the reflected light will not enter the unit to be measured 4 or other optical elements again, avoid interference, and improve the anti-interference ability of the detection system.

[0059] In this embodiment, the light beam collecting module 6 includes a lens and a diaphragm. The lens is installed on the reflected light path of the light splitting plate 3, and its focal point is located on the detector surface of the detector module 7. The diaphragm is arranged on the light path between the lens and the detector module 7, and is used to eliminate other stray light propagating along this light path.

[0060] It can be understood that the lens can effectively collect the backscattered stray light returned from the unit to be measured 4 and focus it on the detector surface, thereby improving the detection sensitivity. The diaphragm can block other irrelevant stray light from entering the detector, thereby further improving the signal-to-noise ratio.

[0061] In this embodiment, the detector module 7 includes a phototube and an amplifier. The phototube is used to convert the received light signal into an electrical signal. The amplifier is used to amplify the electrical signal output by the phototube.

[0062] It can be understood that the phototube can effectively convert the backscattered stray light signal into a measurable electrical signal. The amplifier can amplify this weak electrical signal to a level that can be analyzed and processed by subsequent circuits, thereby further improving the detection sensitivity.

[0063] Embodiment 3

[0064] As shown in Figure 3 , this embodiment proposes a backscattered stray light detection method, which is applied to the backscattered stray light detection device as described in the above embodiments, and includes the following steps:

[0065] S1: Use the light source module 1 to emit a light beam.

[0066] S2: Use the light beam processing module 2 to perform shaping, collimation and / or expansion processing on the light beam emitted by the light source module 1.

[0067] S3: Use the light splitting plate 3 to divide the light beam processed by the light beam processing module 2 into a transmitted light beam and a reflected light beam.

[0068] S4: Set the unit to be measured 4 on the transmitted light path of the light splitting plate 3, receive the transmitted light beam, and generate backscattered stray light.

[0069] S5: Set the light absorbing module 5 on the reflected light path of the light splitting plate 3 to absorb the reflected light beam.

[0070] S6: Set the light beam collecting module 6 between the light splitting plate 3 and the detector module 7 to collect the backscattered stray light returned from the unit to be measured 4 and reflected by the light splitting plate 3.

[0071] S7: Use the detector module 7 connected to the light beam collecting module 6 to receive and detect the backscattered stray light collected by the light beam collecting module 6.

[0072] It can be understood that the backscattered stray light detection method proposed in the embodiment forms the light beam characteristics suitable for subsequent measurement by shaping, collimating and / or expanding the light beam emitted by the light source module 1 through the light beam processing module 2. Then, the light splitting panel 3 divides the processed light beam into a transmitted light beam and a reflected light beam. The transmitted light beam enters the unit to be measured 4 to generate backscattered stray light, while the reflected light beam is absorbed by the light absorption module 5 to prevent it from interfering with the measurement results. In addition, the light beam collection module 6 collects the backscattered stray light returned from the unit to be measured 4 and detects it through the detector module 7. This design not only reduces the influence of external stray light, but also improves the sensitivity and accuracy of detection through the synergistic effect of the light absorption module 5 and the light beam collection module 6, and can improve the detection level to the order of 10-10W, providing more accurate data for gravitational wave measurement, and improving the accuracy and reliability of gravitational wave detection.

[0073] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms is not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present specification and the features of different embodiments or examples without contradiction.

[0074] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "N" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0075] Any process or method descriptions in flow charts or otherwise described herein can be understood as representing code modules, segments, or portions of code that include one or more executable instructions for implementing specific logic functions (or steps) in the process, and the preferred embodiments of the application include additional implementations in which the order of the steps has been changed, additional steps have been added, or some steps have been omitted, without departing from the principles of the application. Such additional implementations should be understood as falling within the scope of the application.

[0076] It should be understood that portions of the present application can be realized with hardware, software, firmware or a combination thereof. In the above embodiments, the N steps or methods can be realized with software or firmware stored in a memory and executed by a suitable instruction execution system. As in another embodiment, if realized with hardware, any one or a combination of the following technologies known in the art can be used: discrete logic circuit with logic gate circuit for implementing logic functions on data signals, application specific integrated circuit with suitable combination logic gate circuit, programmable gate array, field programmable gate array, etc.

[0077] Those skilled in the art can understand that all or part of the steps carried out by the above-mentioned embodiment methods can be completed by programs instructing relevant hardware, and the programs can be stored in a computer readable storage medium. When the program is executed, it includes one of the steps of the method embodiment or a combination thereof.

[0078] Obviously, the above-mentioned embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For those skilled in the art, on the basis of the above description, other different forms of changes or variations can also be made. Here, all the embodiments are not required to be exhausted. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A backscattered stray light detection device, characterized in that, include: Light source module (1), used to emit a light beam; The beam processing module (2) is used to shape, collimate and / or expand the beam emitted by the light source module (1); The beam splitter (3) is used to split the beam processed by the beam processing module (2) into a transmitted beam and a reflected beam. The unit under test (4) is set on the transmission light path of the beam splitter (3) to receive the transmitted beam and generate backscattered stray light; The light absorption module (5) is disposed on the reflected light path of the beam splitter (3) and is used to absorb the reflected light beam; A beam collecting module (6) is disposed between the beam splitting plate (3) and the detector module (7) for collecting backscattered stray light returning from the unit under test (4) and reflected by the beam splitting plate (3); the beam collecting module (6) includes a lens and an aperture; the lens is installed on the reflected light path of the beam splitting plate (3), and its focal point is located on the detector surface of the detector module (7); the aperture is disposed on the light path between the lens and the detector module (7) for eliminating other stray light propagating along this light path; The detector module (7) is connected to the beam collecting module (6) and is used to receive and detect the backscattered stray light collected by the beam collecting module (6); The reflected light path between the beam splitter (3) and the unit under test (4), and the reflected light path between the beam splitter (3) and the beam collection module (6) are connected by a light shield (8); the beam splitter (3) is a circular plate with a diameter of 25 mm and a thickness of 10.06 mm, including an incident surface and an exit surface; the incident surface of the beam splitter (3) is coated with an anti-reflection film, and the exit surface is coated with a semi-transparent and semi-reflective film; the beam splitter (3) is tilted so that the beam is incident at an angle of 50° on the beam incident surface; both the incident surface and the exit surface of the beam splitter (3) are provided with light-transmitting apertures, which are elliptical apertures with a major axis of 7.78 mm and a minor axis of 5 mm; the area of ​​the beam splitter (3) other than the light-transmitting aperture is coated with a black coating. The light source module (1), beam processing module (2), beam splitting plate (3), light absorption module (5), beam collection module (6) and detector module (7) are all housed in a black box, and the inner wall of the black box is coated with black paint.

2. The backscattered stray light detection device according to claim 1, characterized in that, The light absorption module (5) includes a light trap, the residual reflectivity of which is 10. -6 the following.

3. The backscattered stray light detection device according to claim 1, characterized in that, The detector module (7) includes a phototube and an amplifier; The phototube is used to convert the received optical signal into an electrical signal; The amplifier is used to amplify the electrical signal output by the phototube.

4. The backscattered stray light detection device according to claim 1, characterized in that, The light source module (1) emits a 1064nm laser beam.

5. A method for detecting backscattered stray light, applied to the backscattered stray light detection device as described in any one of claims 1 to 4, characterized in that, include: A beam of light is emitted using the light source module (1); The beam processed by the beam processing module (2) is used to shape, collimate and / or expand the beam emitted by the light source module (1); The beam processed by the beam processing module (2) is divided into a transmitted beam and a reflected beam by the beam splitter (3); The unit under test (4) is placed in the transmission light path of the beam splitter (3) to receive the transmitted beam and generate backscattered stray light; A light absorption module (5) is set in the reflected light path of the beam splitter (3) to absorb the reflected light beam; A beam collection module (6) is set between the beam splitter (3) and the detector module (7) to collect the backscattered stray light that returns from the unit under test (4) and is reflected by the beam splitter (3); The backscattered stray light collected by the beam collection module (6) is received and detected by the detector module (7) connected to the beam collection module (6).

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